[vtkusers] Please help with very simple perspective projection question

[Greg Scott]

Hi there,

Can someone please explain to me the functions I must use to

(a) To set the focal length of the perspective projection (i.e. distance
from camera to view plane). Isn't this different to simply setting the focal
point? (I.e. focal point is just where the camera is looking)
(b) Alter the aspect ratio of the projection, i.e. the relative X and Y
scales of the projection

I have asked this before, and looked through the manual and archives, and
found nothing that explicitly specifies a solution.

Many thanks for any help

Greg